Tests for the toxicity of tributyltin (TBT) were conducted on mysid collected from Dadepo beach, Pusan, Korea. The toxic effects of tributyltin on the survival, growth and oxygen consumption of the mysid, Neomysis awatschensis have been evaluated. Mysids were exposed to several concentrations of TBT (0, 0.56, 1.15, 3.07 and 6.12 $mu extrm{g}$/L) for 6 weeks. Survival rate was decreased with increases in concentration and exposure time and the reduction of more than 40％ occurred at TBT concentration greater than 1.15 $mu extrm{g}$/L after 6 weeks. Growth rate was significantly decreased at concentrations greater than 1.15 $mu extrm{g}$/L. Oxygen consumption rate was also decreased in a concentration-dependent way and significantly decreased to 39,47 and 69％ of the control at 1.15, 3.07 and 6.12 $mu extrm{g}$/L, respectively. These results indicate that the contamination of aquatic environment by TBT has the potential to significantly reduce coastal and estuaries recruitment of mysids.